Development deffect preventing process and material

ABSTRACT

A composition for reducing development defects comprising an acidic composition containing, for example, a surfactant applied onto a chemically amplified photoresist coating formed on a substrate having a diameter of 8 inches or more. By this process, the surface of the resist is rendered hydrophilic and the formation of slightly soluble layer in a developer on the surface of the resist is prevented. In addition, by proper diffusion amount of acid from the composition for reducing development defects, the amount of reduction in thickness of the chemically amplified photoresist coating after development is increased by 10 Å to 500 Å in comparison with the case of not applying the composition for reducing development defects to form a resist pattern not having a deteriorated pattern profile such as T-top or round top.

TECHNICAL FIELD

[0001] This invention relates to a process for forming a resist patternhaving less development defects and good profiles using a chemicallyamplified photoresist, and to a composition for reducing developmentdefects used in this process. More particularly, it relates to a processfor forming a resist pattern which can form a resist pattern with goodprofiles by patternwise exposing a large-diameter substrate havingformed thereon a chemically amplified photoresist coating, withpreventing generation of development defects all over the large-diametersubstrate, and to a composition for reducing development defects used inthis process.

BACKGROUND ART

[0002] In manufacturing semiconductor elements, lithographic technologyhas been employed in which a photoresist coating is formed on asubstrate such as a silicon wafer and, after selectively irradiatingthis with actinic rays, is subjected to development processing tothereby form a resist pattern on the substrate.

[0003] In recent years, in order to attain much higher degree ofintegration in LSI, patterning technology to form patterns with a finerline width by a lithographic process has made a rapid progress. Forforming a pattern with a finer line width, various proposals have beenmade with respect to all steps of the lithography and all materials tobe used therein including photoresists, antireflective coatings,exposing methods, exposing apparatus, developing agents, developingprocesses and developing apparatus. For example, Japanese Patent No.2643056 and Japanese Unexamined Patent Publication No. H7-181685describe that an antireflective surface layer containing afluorine-containing compound with a low refractive index is formed on aresist layer to thereby prevent detrimental influences of reflectedlight from the resist surface on formation of a resist pattern. To forman antireflective layer on a resist layer provides the advantage that,since degree of vibration amplitude of the thickness of a resist coatingvs. sensitivity curve becomes smaller, fluctuation in sensitivity ofresist becomes smaller even when thickness of the resist layerfluctuates, which leads to a decreased fluctuation in dimension ofresist patterns formed. In addition, antireflective surface layer servesto decrease standing wave to be caused by interference between incidentlight and reflected light or between one reflected light and anotherreflected light. Recently, technology of forming a resist pattern havinga desired line width without providing the antireflective surface layerhas also been developed. For example, an underlying substrate is madeplane to depress fluctuation in dimension due to fluctuation inthickness of the resist layer as described above, or a mask pattern isfinely adjusted according to fluctuation in dimension of the resist.

[0004] With regard to exposing apparatus, there has been proposed aprocess of using a light source emitting radiation of a shortwavelength, which is advantageous for forming a finer pattern, such asdeep UV rays of KrF excimer laser (248 nm) or ArF excimer laser (193 nm)or, further, X rays or electron beams, and some of them have been cominginto practice.

[0005] On the other hand, improvement in the yield of semiconductorintegrated circuits has occupied the attention as an extremely importantmatter in manufacturing them. There exist many factors that decide theyield of semiconductor integrated circuits. One of the factors ispatterning failure upon forming a pattern using a resist. Thispatterning failure of a resist pattern is caused, for example, by dustexisting in or on the surface of the resist, by deterioration of theresist due to floating chemical species in a clean room, by coatingfailure of the resist or the like, or by development failure. As anexample of deterioration due to chemical species in a clean room, thereis illustrated that which is caused in the process using a chemicallyamplified photoresist. In this process, the chemically amplifiedphotoresist is so susceptible to the influence of acidic substances,basic substances and moisture in the atmosphere that there results achange in dimension of a pattern—for example, a T-topped resist patternresults when a positive-working photoresist is used, or a round-toppedresist pattern results when a negative-working photoresist is used—incase when the period between patternwise exposure to PEB (post exposurebake) is prolonged or due to intermixing with a resist.

[0006] In addition, defects upon developing a resist coating have becomea problem. For example, there are illustrated scumming in line-and-spacetype resists and opening failure in contact hole type resists. Severalcauses may be considered for the opening failure of contact holes, butthe most popular opening failure is that which is caused by residuesafter development. As the causes for these defects, there is illustratedinsufficient dissolution of exposed portions into a developing solutiondue to insufficient contact between the developing solution containingwater as a major component and the surface of a resist upon bringing thedeveloping solution into contact with the resist surface, which leads toopening failure of portions which are designed to open. It is alsopossible that insolubles for the developing solution might redepositonto the surface of the resist upon rinsing with water afterdevelopment.

[0007] Further, it is necessary to enhance contrast of a resist in orderto form a finer pattern. In general, in order to improve contrast of acontact hole type resist, a technique of increasing a protecting ratioof hydrophilic groups in a major component polymer is used with respectto, for example, positive-working chemically amplified photoresists.However, when the protecting ratio is increased, the resist surface isliable to become hydrophobic, leading to deterioration in wettingproperties for the developing solution.

[0008] Various investigations have been conducted to solve theabove-described problems. For example, Japanese Unexamined PatentPublication No. H9-246166 proposes to treat the surface of a photoresistwith plasma to thereby render the surface hydrophilic, thus improvingwetting properties of the resist for a developing solution anddecreasing development defects. This technique, however, requiresintroduction of an additional apparatus for the plasma treatment andinvolves the problem of decrease in throughput.

[0009] In addition, various attempts for decreasing the developmentdefects by optimizing development sequence have been made as well. Forexample, Japanese Examined Patent Publication No. H4-51020 describes toimprove wetting properties of a positive-working resist for a developingsolution by adding an acetylenealcohol type surfactant to the developingsolution, thereby forming a pattern having no development defects.Although some effects can be obtained by this technique, the effects areat present still insufficient in ultra-fine working using the aforesaidchemically amplified photoresists. In addition, Japanese UnexaminedPatent Publication No. S61-179435 describes to optionally conductsurface coating, which is effective for improving wetting properties fora developing solution, in addition to the method of adding a surfactantto the developing solution and the method of plasma-treating the surfaceof a resist coating, for preventing development defects resulting fromlack of wetting properties for the developing solution.

[0010] However, particularly in case when surface coating for decreasingthe development defects is conducted on a chemically amplifiedphotoresist, there results a T-topped pattern if the surface coatingcomposition contains a compound, such as a basic compound, whichdeactivates an acid generated at patternwise exposure. On the otherhand, in case when this surface coating gives an excess amount of acidto the photoresist layer, there results an extreme reduction inthickness of coating in unexposed portions, which might lead toformation of a round topped resist pattern which constitutes an obstaclein an etching process.

[0011] Further, problems in attaining uniform thickness of coating anduniform development to be caused with a recent increase in diameter of asubstrate such as a silicon wafer are said to make it difficult to forma finer pattern. For example, a paddle developing method has so far beenpopularly employed for developing a resist coating on the silicon wafer.In the paddle developing method, a developing solution is dropped onto aresist coating formed on a substrate, and the substrate is spun to forma thin film of the developing solution all over the resist coating, thusdevelopment of the resist coating being conducted. However, theregenerates a difference in circumferential speed between the centralportion and the peripheral portion of the substrate, thereby adifference in speed of the coating generating. Thus, developingconditions become different between the central portion of the wafer andthe peripheral portion thereof. In this situation, particularly when achemically amplified photoresist is used as a resist and alarge-diameter substrate having a diameter of 8 inches or more is used,development defects in the peripheral portion are caused in some caseswhich have not conventionally been observed in treating a resist coatingformed on a substrate having a diameter of 6 inches or less.

[0012] Therefore, in order to improve a yield in manufacturingsemiconductor integrated circuits and so on, a process for forming aresist pattern has been desired earnestly which enables one to reducedevelopment defects to be caused upon development including developmentdefect to be caused in the periphery of a chemically amplifiedphotoresist formed on a larger diameter substrate such as a siliconwafer, and which does not cause pattern failure such as T-top or roundtop after development, thus being adapted for forming a finer resistpattern.

[0013] In consideration of the above-described situation, an object ofthe present invention is to provide a process for forming a resistpattern which can reduce development defects of a chemically amplifiedphotoresist, formed on a large diameter substrate having a diameter of 8inches or more, to be caused upon development and which does not causedeterioration of pattern profiles such as T-top or round topinconvenient for an etching step due to detrimental influences of aprocessing atmosphere and intermixing between the surface coating andthe resist, and a composition for reducing development defects in thisprocess.

DISCLOSURE OF THE INVENTION

[0014] As a result of intensive investigations, the inventors have foundthat the above-described object can be attained by increasing the amountof reduction in thickness of a resist after development in comparisonwith the case of not coating a composition for reducing developmentdefects in a pattern-forming process wherein the composition forreducing development defects is applied on a chemically amplifiedphotoresist coating formed on a substrate in order to render the surfaceof photoresist hydrophilic, followed by patternwise exposure anddevelopment to obtain a resist pattern, thus having achieved the presentinvention based on the finding.

[0015] That is, the present invention is a process for forming a resistpattern which includes: a step of forming a chemically amplifiedphotoresist coating on a substrate having a diameter of 8 inches or moreby application; a step of applying a composition for reducingdevelopment defects on the chemically amplified photoresist coating; astep of baking after at least either the step of forming the chemicallyamplified photoresist coating by application or the step of applying thecomposition for reducing development defects; a step of selectivelyexposing the chemically amplified photoresist coating; a step ofpost-exposure baking the chemically amplified photoresist coating; and astep of developing the chemically amplified photoresist coating, andwhich increases the amount of reduction in thickness of the chemicallyamplified photoresist coating after development by 10 Å to 500 Å incomparison with the case of not applying the composition for reducingdevelopment defects.

[0016] In addition, the present invention is a composition for reducingdevelopment defects which is composed of an acidic compositioncontaining a surfactant and which is to be used for the process forforming a resist pattern which includes: a step of forming a chemicallyamplified photoresist coating on a substrate having a diameter of 8inches or more by application; a step of applying a composition forreducing development defects on the chemically amplified photoresistcoating; a step of baking after at least either the step of forming thechemically amplified photoresist coating by application or the step ofcoating the composition for reducing development defects; a step ofselectively exposing the chemically amplified photoresist coating; astep of post-exposure baking the chemically amplified photoresistcoating; and a step of developing the chemically amplified photoresistcoating, and which increases the amount of reduction in thickness of thechemically amplified photoresist coating after development by 10 Å to500 Å in comparison with the case of not applying the composition forreducing development defects.

[0017] The present invention is described in more detail below.

[0018] In the process of the present invention for forming a resistpattern, it is necessary to increase the amount of reduction inthickness of the chemically amplified photoresist after development by10 Å to 500 Å in comparison with the case of not coating the compositionfor reducing development defects. In the present invention, thechemically amplified photoresist may be either of positive-working andnegative-working types. The composition for reducing development defectsto be used in the present invention preferably contains a surfactantand, when the chemically amplified photoresist is positive-working, thecomposition for reducing development defects is preferably acidic. PH ofthe composition is preferably 1.5 to 4.5, more preferably 1.7 to 3.5. Inaddition, when the chemically amplified photoresist is negative-working,the composition is preferably weakly acidic to alkaline.

[0019] As the surfactant to be used in the composition of the presentinvention for reducing development defects, industrially utilizedorganic acids or the amine or ammonium salts thereof are preferablyused. As the organic acid, functional fluorocarbon compounds arepreferred. Of the functional fluorocarbon compounds, C₄ to C₁₅perfluoroalkylcarboxylic acids and the ammonium salts,tetramethylammonium salts or C₁ to C₄ alkanolamine salts thereof; C₄ toC₁₀ perfluoroalkylsulfonic acids and the ammonium salts,tetramethylammonium salts or C₁ to C₄ alkanolamine salts thereof;fluorinated alkyl quaternary ammonium iodides; and perfluoroadipic acidand the quaternary ammonium salts thereof are preferred, withtetramethylammonium salts of C₇ to C₁₀ perfluoroalkylcarboxylic acids,C₄ to C₈ perfluoroalkylsulfonic acids and the C₁ to C₄ alkanolaminesalts thereof being more preferred. As the amine salts or ammonium saltsof the organic acids, previously prepared salts may be used, or thoseformed by mixing an organic acid and a base such as an amine or ammoniain an aqueous solution may be used as well.

[0020] These surfactants are used as a 0.1 wt %-25 wt %, more preferably2 wt %-4 wt % aqueous solution for the composition for reducingdevelopment defects. In this situation, it is preferred to optimize theamount of reduction in thickness of the resist layer by properlyadjusting the mixing ratio of the organic acid to the base such as amineor ammonia or adjusting basicity of the composition in consideration ofthe kind of a chemically amplified photoresist to be used or processingconditions. That is, in the case of using, for example, apositive-working photoresist as the chemically amplified photoresist, itsuffices to adjust, upon using a salt between the organic acid and theamine or ammonium as the surfactant, the mixing ratio of the organicacid to the amine or ammonium so that pH of the composition for reducingdevelopment defects becomes at an optimal pH within the above-describedrange. It has been found that, in this mixing, better results can oftenbe obtained when the organic acid is used in an amount more than theequivalent amount of the base, than when the surfactant is whollycomposed of the organic acid or the salt between the organic acid andthe amine or ammonium. Thus, optimal results can be obtained byadjusting the amount of reduction in thickness of resist coating upondevelopment through adjustment of the mixing ratio of the organic acidto the base such as amine or ammonia to thereby properly adjust pHdepending upon kind of the chemically amplified photoresist to be usedor processing conditions. In the composition for reducing developmentdefects to be applied to a positive-working chemically amplifiedphotoresist, the ratio of the organic acid to the base (for example,amine) is usually about 7:0-7:6 in molar ratio, preferably about7:4-7:6, more preferably about 7:5. In terms of organic acid: salt, themolar ratio is usually about 7:0-1:6, preferably about 3:4-1:6, morepreferably about 2:5.

[0021] To the composition of the present invention for reducingdevelopment defects may further be added, if necessary, water-solubleresins and various additives within amounts not spoiling performance ofthe composition.

[0022] As the water-soluble resin to be used in the composition forreducing development defects of the present invention, there may beillustrated, for example, poly(vinyl alcohol), poly(acrylic acid),poly(vinylpyrrolidone), poly(α-trifluoromethylacrylic acid), poly(vinylmethyl ether-co-maleic anhydride), poly(ethylene glycol-co-propyleneglycol), poly(N-vinylpyrrolidone-co-vinyl acetate),poly(N-vinylpyrrolidone-co-vinyl alcohol),poly(N-vinylpyrrolidone-co-acrylic acid),poly(N-vinylpyrrolidone-co-methyl acrylate),poly(N-vinylpyrrolidone-co-methacrylic acid),poly(N-vinylpyrrolidone-co-methyl methacrylate),poly(N-vinylpyrrolidone-co-maleic acid),poly(N-vinylpyrrolidone-co-dimethyl maleate),poly(N-vinylpyrrolidone-co-maleic anhydride),poly(N-vinylpyrrolidone-co-itaconic acid),poly(N-vinyl-pyrrolidone-co-methyl itaconate),poly(N-vinylpyrrolidone-co-itaconicanhydride, and fluorinatedpolyether,withpoly-(acrylic acid), poly(vinylpyrrolidone) and fluorinatedpolyether being particularly preferred.

[0023] As the additives to be used in the composition for reducingdevelopment defects of the present invention, there may be illustrated,for example, surfactants to be added for improving coating properties,such as nonionic surfactants, anionic surfactants and amphotericsurfactants. The nonionic surfactants are exemplified by polyoxyethylenealkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene oleylether and polyoxyethylene cetyl ether, polyoxyethylene fatty aciddiesters, polyoxyfatty acid monoester, polyoxyethylene-polyoxypropyleneblock polymer, and acetylene glycol derivatives, the anionic surfactantsare exemplified by alkyldiphenyl ether disulfonic acids and the ammoniumsalts or organic amine salts thereof, alkyldiphenyl ether sulfonic acidsand the ammonium salts or organic amine salts thereof,alkylbenzenesulfonic acids and the ammonium salts or organic amine saltsthereof, polyoxyethylene alkyl ether sulfuric acids and the ammoniumsalts or organic amine salts thereof, and alkyl sulfuric acids and theammonium salts or organic amine salts thereof, and the amphotericsurfactants are exemplified by2-alkyl-N-carboxymethyl-N-hydroxyethyl-imidazolinium betaine andlaurylamidopropyl hydroxysulfone betaine.

[0024] Further, as water to be used in the composition for reducingdevelopment defects of the present invention, water from which organicimpurities, metal ions, etc. have been removed by distillation,ion-exchange treatment, treatment through filter or various adsorptiontreatments are preferably used.

[0025] Additionally, in order to improve coating properties, awater-soluble organic solvent may be used together with water. Thewater-soluble organic solvent is not particularly limited as long as itcan be soluble in water in a concentration of 0.1 wt % or more. Examplesof the organic solvent include alcohols such as methyl alcohol, ethylalcohol and isopropyl alcohol, ketones such as acetone and methyl ethylketone, esters such as methyl acetate and ethyl acetate, and polarsolvents such as dimethylformamide, dimethylsulfoxide, methylcellosolve, cellosolve, butyl cellosolve, cellosolve acetate,butylcarbitol and carbitol acetate. These specific examples are merelyillustrated as examples of the organic solvents, and the organicsolvents to be used in the present invention are not limited only tothese solvents.

[0026] In addition, optimization of reduction in thickness of resistcoating in the present invention may also be attained by properlyadjusting baking time or baking temperature of the resist and thecomposition for reducing development defects as well as optimization bythe composition itself for reducing development defects. As to theprebaking temperature for the resist, there are generally two types inaccordance with photoresist compositions to be used. That is, one typerequires a high energy and generally requires to bake at a temperatureof about 100 to 150° C., and another type does not require so muchenergy in comparison with the former and requires to bake at atemperature of 100° C. or lower. In addition, prebaking temperature forthe composition for reducing development defects is generally 60 to 100°C. which is high enough to remove the solvent. Further, post-exposurebaking of the resist is generally about 100 to 150° C. For example, incase when T-tops are formed after development, formation of such T-topscan be in some cases avoided by such combination of baking temperaturesfor the resist and the composition for reducing development defects thatresist-prebaking temperature is set at a lower level while prebakingtemperature for the composition for reducing development defects at alevel of 100° C. or higher. In addition, too much reduction in thicknessof the resist coating disadvantageous in an etching step can be avoidedby optionally delaminating or dissolving away the composition forreducing development defects after exposure.

[0027] Thickness of the coating of the composition for reducingdevelopment defects in the present invention may be such that itprovides enough chemical action to more reduce thickness of the resistcoating in comparison with the case of not applying the composition forreducing development defects, and is preferably 80 to 10000 Å, morepreferably 330 to 990 Å. Coating of the composition for reducingdevelopment defects can be conducted by any of known coating methodssuch as a spin coating method.

[0028] The chemically amplified photoresist to be used in the presentinvention as a resist may be any of known positive-working andnegative-working chemically amplified photoresists. As thepositive-working chemically amplified photoresist, there are known anumber of ones including that which is composed of a combination of apolymer wherein polyhydroxystyrene is protected with t-butoxycarbonylgroup and a photo acid generator (see, H. Ito, and C. G. Willson: Polym.Eng. Sci., 23, 1012 (1983)). Also, as the negative-working chemicallyamplified photoresist, there may be illustrated, for example, that whichis composed of an alkali-soluble resin, a cross-linking agent ofhexamethoxymelamine and a photo acid generator (for example, see, W. E.Feely, J. C. Imhof, C. M. Stein, T. A. Fisher and M. W. Legenza: Polym.Eng. Sci., 26, 1101(1986)). Of these, positive-working chemicallyamplified photoresists are preferred in the present invention. Thicknessof the coating may be such that a resist pattern obtained afterdevelopment can suitably exert its performance during etching in theetching step, and is generally about 0.3 to 1.0 μm.

[0029] The pattern-forming method of the present invention can favorablybe applied upon formation of a pattern on a substrate having a diameterof 8 inches or more. As the substrate, a silicon substrate is common,but may of course be those wherein a metal layer or a oxide or nitridelayer such as silicon oxide, silicon nitride or silicon oxide nitride isformed on silicon. In addition, the substrate itself is not limited tosilicon but may be any of substrate materials having so far been usedfor manufacturing IC such as LSI.

[0030] As to the method for coating the chemically amplifiedphotoresist, baking of the chemically amplified photoresist layer andthe layer of reducing development defect compositions, exposing method,developing agents, and developing methods, any ones or any conditionshaving so far been employed for forming a resist pattern using achemically amplified photoresist may be employed. Further, as anexposing light source to be used in the exposing step, any of UV rays,deep UV rays, X rays and electron beams may be used.

[0031] Best Mode for Practicing the Invention

[0032] The present invention will now be described more specifically byreference to Examples which, however, are not to be construed to limitthe present invention in any way. Additionally, in the followingExamples, “parts” are by weight unless otherwise specified.

EXAMPLE 1

[0033] 3 parts of perfluorooctanesulfonic acid, 0.35 part of2-aminoethanol and 1 part of polyvinylpyrrolidone having a molecularweight of 45,000 were dissolved uniformly in 95.65 parts of pure waterat the room temperature, and the resultant mixture was passed through a0.05-μm filter to obtain a composition for reducing development defects.This composition for reducing development defects had a pH of about 2.3.

[0034] Separately, a positive-working chemically amplified photoresistcontaining a p-hydroxystyrene derivative was applied on an 8-inchsilicon wafer in a varying thickness. Thus, there were prepared wafershaving coated thereon the photoresist coating in a varying thickness offrom about 0.67 μm to 0.81 μm after being prebaked. The prebaking wasconducted at 90° C. for 90 seconds. Thereafter, the above-describedcomposition for reducing development defects was applied on each of thewafers in a thickness of 440 Å (without baking). Exposure was conductedusing a halftone phase shift mask for contact hole having a mask size of0.28 μm. FPA3000EX5 made by Canon Co., Ltd. was used for conducting theexposure. After conducting PEB at 120° C. for 90 seconds, each wafer wasdevelopment processed for 60 seconds in a 2.38% TMAH(tetramethylammonium hydroxide). In the development processing, E2nozzles were used employing a soft impact method. Of the patterns thusformed, patterns of 0.20 μm in hole diameter and 1:1, 1:3 or 1:5 inhole-to-hole distance were observed under CD-SEM, S9200 made by HitachiCo., Ltd. Results thus obtained are tabulated in Table 1. In Table 1,“no problem” means that all hole patterns were opened with apredetermined diameter. TABLE 1 With Composition for ReducingDevelopment Defects (Development: Soft Impact) 1:1 1:3 1:5 Proper ProperProper Thickness of Resist Thickness of Resist Amount of RedictionExposure Exposure Exposure Coating Before Coating After in Thickness ofResist Amount Observed Amount Observed Amount Observed Development (nm)Development (nm) Coating (nm) (mJ/cm²) Pattern (mJ/cm²) Pattern (mJ/cm²)Pattern 669 603 66 14 No problem 18 No problem 19 No problem 682 618 6413 No problem 18 No problem 18.5 No problem 688 622 66 13 No problem 18No problem 19 No problem 698 632 66 12.5 No problem 18 No problem 19 Noproblem 705 639 66 12.5 No problem 18.5 No problem 19.5 No problem 716649 67 12.5 No problem 19.5 No problem 20 No problem 730 662 68 13.5 Noproblem 19.5 No problem 20 No problem 740 671 68 14 No problem 19 Noproblem 20 No problem 750 682 68 14 No problem 19 No problem 20 Noproblem 760 691 69 13 No problem 19 No problem 19.5 No problem 772 70271 12.5 No problem 18.5 No problem 20 No problem 783 711 72 13 Noproblem 18.5 No problem 21.5 No problem 794 722 73 13.5 No problem 19 Noproblem 21.5 No problem 807 736 72 14.5 No problem 19.5 No problem 21.5No problem

COMPARATIVE EXAMPLE 1

[0035] Silicon wafers having coated thereon a positive-workingchemically amplified photoresist with a varying thickness after bakingwere prepared in the same manner as in Example 1. Subsequentdevelopment, PEB and development were conducted in the same manner as inExample 1 except for not coating the composition for reducingdevelopment defects, and the wafers were observed under CD-SEM in thesame manner as in Example 1. Results thus obtained are shown in Table 2.In comparison with Example 1, a number of development defects wereobserved. Additionally, “Opening failure was observed” means thereexisted some hole patterns not opened with a predetermined diameter.TABLE 2 Without Composition for Reducing Development Defects(Development: Soft Impact) 1:1 1:3 1:5 Amount of Proper Proper ProperThickness of Resist Thickness of Resist Reduction in Exposure ExposureExposure Coating Before Coating After Thickness of Resist AmountObserved Amount Observed Amount Observed Development (nm) Development(nm) Coating (nm) (mJ/cm²) Pattern (mJ/cm²) Pattern (mJ/cm²) Pattern 674632 42 12 No problem 18.5 No problem 21 No problem 681 641 40 14.5 Noproblem 21 No problem 23.5 No problem 692 649 43 17 No problem 24 Noproblem 25.5 No problem 701 658 44 18 No problem 23.5 No problem 26 Noproblem 711 667 44 17 Opening failure 22.5 Opening failure 23.5 Openingfailure was observed was observed was observed 716 670 46 16.5 Openingfailure 20.5 Opening failure 21 Opening failure was observed wasobserved was observed 728 683 45 12.5 Opening failure 18 Opening failure19.5 Opening failure was observed was observed was observed 739 694 4512 No problem 20.5 No problem 21 No problem 749 703 46 14 No problem 21No problem 23 No problem 759 714 46 16.5 No problem 23 No problem 25.5No problem 771 725 46 18.5 No problem 25 No problem 26.5 No problem 782736 46 17.5 Opening failure 22.5 Opening failure 25 Opening failure wasobserved was observed was observed 793 747 47 14.5 Opening failure 20.5Opening failure 21.5 Opening failure was observed was observed wasobserved 806 759 47 12.5 No problem 20 No problem 20 No problem

COMPARATIVE EXAMPLE 2

[0036] Silicon wafers having coated thereon a positive-workingchemically amplified photoresist with a varying thickness after bakingwere prepared in the same manner as in Example 1. Subsequentdevelopment, PEB and development were conducted in the same manner as inExample 1 except for not coating the composition for reducingdevelopment defects and changing the developing method to a sprayingmethod, and the wafers were observed under CD-SEM in the same manner asin Example 1. Results thus obtained are shown in Table 3. It is seenthat, although development was conducted according to spraying method(paddle development as in Comparative Example 1) in which developmentdefects are rather difficult to take place in comparison with the softimpact method due to more strict developing conditions employed in thespraying method, removal of development defects are still insufficientin comparison with Example 1 though better than in ComparativeExample 1. TABLE 3 Without Composition for Reducing Development Defects(Development: Spraying) 1:1 1:3 1:5 Amount of Proper Proper ProperThickness of Resist Thickness of Resist Reduction in Exposure ExposureExposure Coating Before Coating After Thickness of Resist AmountObserved Amount Observed Amount Observed Development (nm) Development(nm) (nm) (mJ/cm²) Pattern (mJ/cm²) Pattern (mJ/cm²) Pattern 667 632 3511 No problem 17.5 No problem 19.5 No problem 678 641 37 13 No problem20 No problem 22 No problem 684 649 35 15.5 No problem 21.5 No problem23 No problem 697 658 40 18 No problem 24 No problem 25.5 No problem 708667 41 17 No problem 22 No problem 23.5 No problem 720 670 50 14 Noproblem 19.5 Opening failure 20 Opening failure was observed wasobserved 731 683 48 12 No problem 18.5 No problem 20 No problem 741 69448 12 No problem 19.5 No problem 21 No problem 752 703 49 14.5 Noproblem 21 No problem 22.5 No problem 763 714 49 17 No problem 22.5 Noproblem 25 No problem 771 725 46 18 No problem 24 No problem 26.5 Noproblem 782 736 46 17 No problem 22 Opening failure 24 No problem wasobserved 794 747 47 14 Opening failure 19.5 Opening failure 20.5 Openingfailure was observed was observed was observed 807 759 49 12 No problem19.5 No problem 21 No problem

ADVANTAGES OF THE INVENTION

[0037] As has been described in detail hereinbefore, the resistpattern-forming process of the present invention can form a resistpattern with good profiles which does not cause deterioration of patternprofile such as formation of T-top or round top and which, even whensubstrates having a diameter of 8 inches or more is used, does not causedevelopment defects.

1. (amended) a process for forming a resist pattern which includes: astep of forming a chemically amplified photoresist coating on asubstrate having a diameter of 8 inches or more by application; a stepof applying a composition for reducing development defects on thechemically amplified photoresist coating; a step of baking after atleast either the step of forming the chemically amplified photoresistcoating by application or the step of applying the composition forreducing development defects; a step of selectively exposing thechemically amplified photoresist coating; a step of post-exposure bakingthe chemically amplified photoresist coating; and a step of developingthe chemically amplified photoresist coating, said composition forreducing development defects comprises an acidic composition containinga surfactant and which increases the amount of reduction in thickness ofthe chemically amplified photoresist coating after development by 10 Åto 500 Å in comparison with the case of not applying the composition forreducing development defects.
 2. (Deleted)
 3. (Amended) The process forforming resist patterns according to claim [2] 1, wherein the surfactantis at least one member selected from the group consisting of C₄ to C₁₅perfluoroalkylcarboxylic acids and the ammonium salts,tetramethylammonium salts or C₁ to C₄ alkanolamine salts thereof, C₄ toC₁₀ perfluoroalkylsulfonic acids and the ammonium salts,tetramethylammonium salts or C₁ to C₄ alkanolamine salts thereof,fluorinated alkyl quaternary ammonium iodides, perfluoroadipic acid andthe quaternary ammonium salts thereof.
 4. A composition for reducingdevelopment defects which is composed of an acidic compositioncontaining a surfactant and which is to be used for the process forforming a resist pattern which includes: a step of forming a chemicallyamplified photoresist coating on a substrate having a diameter of 8inches or more by application; a step of applying a composition forreducing development defects on the chemically amplified photoresistcoating; a step of baking after at least either the step of forming thechemically amplified photoresist coating by application or the step ofapplying the composition for reducing development defects; a step ofselectively exposing the chemically amplified photoresist coating; astep of post-exposure baking the chemically amplified photoresistcoating; and a step of developing the chemically amplified photoresistcoating, and which increases the amount of reduction in thickness of thechemically amplified photoresist coating after development by 10 Å to500 Å in comparison with the case of not applying the composition forreducing development defects.
 5. The composition for reducingdevelopment defects according to claim 4, wherein the surfactant is atleast one member selected from the group consisting of C₄ to C₁₅perfluoroalkylcarboxylic acids and the ammonium salts,tetramethylammonium salts or C₁ to C₄ alkanolamine salts thereof, C₄ toC₁₀ perfluoroalkylsulfonic acids and the ammonium salts,tetramethylammonium salts or C₁ to C₄ alkanolamine salts thereof,fluorinated alkyl quaternary ammonium iodides, perfluoroadipic acid andthe quaternary ammonium salts thereof.